(Bloomberg) -- President Donald Trump has asserted executive privilege over documents concerning plans to add a citizenship question to the 2020 Census, including material being sought by House Democrats through a subpoena, according to the Justice Department.

"These documents are protected from disclosure by the deliberative process, attorney-client communications, or attorney work product components of executive privilege," Assistant Attorney General Stephen Boyd wrote in a letter Wednesday to House Oversight and Reform Chairman Elijah Cummings. "In addition, the president has made a protective assertion of executive privilege over the remainder of the subpoenaed documents."

The move is the latest to stymie and frustrate efforts by House Democrats to investigate actions by the Trump administration. It came as Cummings’s panel prepares to vote to hold Attorney General William Barr and Commerce Secretary Wilbur Ross in contempt.

At issue is the Oversight panel’s investigation into the administration’s efforts to include the citizenship question on the census.

The Justice Department said the committee has abandoned the process for trying to reach an accommodation by choosing to go forward "with an unnecessary and premature contempt vote."

To contact the reporter on this story: Chris Strohm in Washington at cstrohm1@bloomberg.net

To contact the editors responsible for this story: Kevin Whitelaw at kwhitelaw@bloomberg.net, Larry Liebert, Justin Blum

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